Already known from the prior art are hinged closures in one, two or three parts made of plastic, commonly known as sports caps, that allow the consumer to directly drink the liquid contained in a container and to close it again thereafter. In the document WO 2004/007313, there is an illustration of a closure of this type made in two parts, with a first part forming both a base for fastening on to a container neck and a spout to be taken in the mouth, and a second part forming a lid serving to cover and close off the spout, this second part further comprising a fastening ring and a flexible hinged strap connecting the fastening ring to the lid. An advantage of this type of closure is that it can be manufactured in the closed position, that is to say, without an assembly step of closing the closure wherein the lid is pivoted on its articulation, the assembly of the two parts being done by means of a simple translational movement, during which the ring comes to be inserted by its lower portion into a fastening groove provided for this purpose in the base. The ring is additionally also provided in its upper portion with one or more recesses each receiving a first-opening indicator connected on the one hand to the bottom of the recess and on the other hand to a rim flange of the lid. The intended effect is to bring about, when opening, the breaking of the first-opening indicator into two parts, one connected to the lid and the other to the ring, and, by means of a displacement or deformation of at least one of these two parts, to make the opening detectable by the consumer. In practice, however, it proves to be difficult, on closures of small dimensions, to obtain a displacement or deformation that is detectable by the consumer. This is the reason why, for its commercialisation, this closure has been provided with a break away tab in lieu of the first-opening indicator. Thus, precautions must then be taken in order to ensure that this break away tab does not separate from the closure after opening, which would be detrimental from the standpoint of respect for the environment.
In the document EP 1 892 194 a sports cap in two parts has been proposed, that is to say, a first part forming a base and a lid articulatedly joined to the base by a hinge, and a second part constituting a spout inserted into the base. This cap may also be manufactured in the closed position, by means of axial assembly of the two parts. An annular dead volume is maintained between the two assembled parts, this being a volume that serves to house, after opening a first-opening indicator that is separated from a peripheral wall from the cap. In order to ensure proper assembly while preserving this annular dead volume, it is necessary to provide end stops projecting outward axially from the bottom of the base and against which the spout is positioned. Once again the result thereof is a substantial axial space requirement. In addition, the disappearance of the first-opening indicator does not necessarily allow a consumer unfamiliar with the cap mechanism in question to visually discern whether the latter had already been opened. Finally, the fact that the base and the cap belong to the same part limits the possible variations in colour and material for the portion visible externally, unless this part is manufactured by using a bi-injection process, which would raise the cost thereof.